Physics - Unit 2: Circular Motion

Review set for midterms

Motion wants to be in a…

stright line UNLESS acted upon by an outside force

When we see curves on a graph, what has been introduced?

Outside forces

What does centripetal force?

it means “center-seeking”

Centripetal force is always pointing…

inward toward the center of rotation of the curve

What is an example of centripetal force?

A gravitron ride or a car door pushing us in

Can gravity use centripetal forces?

Yes, it keeps objects in orbit

Centripetal force and acceleration are similar because…?

They always point in the same direction (inward)

What would happen if the centripetal force suddenly vanishes?

The linear motion of the object will always be directed at a right angle to the centripetal force (or tangent to the circle) at the point of release and in the same direction as the rotation of the object

What is the angle measure we use instead of degrees?

Radians

Radian is a way of measuring angles…

based on the radius of the circle

Distance now measures how much angle we go through, what is the name of the symbol?

Theta

Speed now measures how fast we cover the angle, what is the name of the symbol?

Omega

Acceleration now measures how quickly a spinning object changes its rate of spin, what is the name of the symbol?

alpha

Displacement formula

Distance (d) = radius (R) x theta

Speed (tangential velocity)

speed (s) = radius (R) x omega

Acceleration formula

acceleration (a) = radius (R) x alpha

Angular (circular) Acceleration and Speed Formula

Angular acceleration = a change in angular speed divided by time (t)

Circular Motion Formula

Centripetal Acceleration = velocity squared / radius a_c = v_t²/r

Centripetal Force Formula

Centripetal force = mass x centripetal acceleration,  F_c = m x a_c

  θ

displacement (radians, rad)

 ω_i

initial rotational speed (radians/second rad/s)

ω_f

final rotational speed (radians/second rad/s)

  α

acceleration (radians/second/second rad/s/s rad/s²)

  t

time (s)

If the rotation is counterclockwise…

the torque is considered positive

If the rotation is clockwise

the torque is considered negative

unbalanced forces =

object is accelerating

balanced forces =

object is in constant motion

Balanced torque

it means that counterclockwise torque equals the clockwise torque which results in NO CHANGE in rotation

Unbalanced torque means

one torque iss bigger than the other, so there is a change in rotational motion (there is rotational acceleration)

Torque formula

Torque = perpendicular force x distance (to the center of rotation), T = F⟂ x d

The formula of Newton’s second law turns into…

T = Iα during this unit